The invention relates to the use of a metal complex as a dopant for doping an organic semiconducting matrix material in order to alter the latter's electrical characteristics, the compound constituting an n-dopant with regard to the matrix material; it also relates to an organic semiconducting material containing an organic matrix material and a metal complex as an n-dopant, and also to an electronic device with an organic semiconducting material which is doped with a metal complex as an n-dopant. The invention further relates to n-dopants and ligands and processes for producing them.
It is known to modify organic semiconductors with regard to their electrical characteristics, especially their electrical conductivity, by doping them, which is also the case with inorganic semiconductors such as silicon semiconductors. In the process, charge carriers are generated in the matrix material in order to increase its conductivity, which is initially quite low, and, depending on the nature of the dopant used, to produce a change in the Fermi level of the semiconductor. In this context, doping leads to an increase in the conductivity of charge transport layers, thus reducing ohmic losses, and to an improved passage of the charge carriers between the contacts and the organic layer. In organic matrix materials, inorganic dopants are generally disadvantageous because of their high diffusion coefficients, since they impair the functioning and stability of the electronic devices. In addition, it is known to release dopants by means of chemical reactions in the semiconducting matrix material, in order to provide dopants. However, the oxidation potential of the dopants released in this way is often not sufficient for various applications, such as for organic light-emitting diodes (OLED) in particular. Furthermore, when the dopants are released, other compounds and/or atoms are produced, such as atomic hydrogen for example, as a result of which the characteristics of the doping layer or the corresponding electronic device are impaired.
What is more, organic compounds used as dopants often do not have a sufficiently low oxidation potential for the application in question.